Physical vapor deposition targets

ABSTRACT

A physical vapor deposition target includes an alloy of copper and silver, with the silver being present in the alloy at from less than 1.0 at % to 0.001 at %. In one implementation, a physical vapor deposition target includes an alloy of copper and silver, with the silver being present in the alloy at from 50 at % to 70 at %. A physical vapor deposition target includes an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %. In one implementation, a conductive integrated circuit metal alloy interconnection includes an alloy of copper and silver, with the silver being present in the alloy at from less than 1.0 at % to 0.001 at %. A conductive integrated circuit metal alloy interconnection includes an alloy of copper and silver, with the silver being present in the alloy at from 50 at % to 70 at %. A conductive integrated circuit metal alloy interconnection includes an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %. Other useable copper alloys include an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, Te, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Au, Tl, and Pb. An electroplating anode is formed to comprise one or more of the above alloys.

TECHNICAL FIELD

[0001] This invention relates to physical vapor deposition targets, toconductive integrated circuit metal alloy interconnections, and toelectroplating anodes.

BACKGROUND OF THE INVENTION

[0002] Aluminum and its alloys are common metal materials used in metalinterconnects in the fabrication of integrated circuitry onsemiconductor wafers. Yet as circuitry density increases and operatingspeed increases, aluminum's electrical resistance is expected to preventits use in many next generation circuits. Copper has been proposed as astrong candidate to replace aluminum and its alloys due to copper's lowbulk resistivity of 1.7 microohms.cm at near 100% purity (i.e., greaterthan 99.999% copper). Further, it has electromigration resistancecompared to that of aluminum and its alloys of about 10 times orgreater.

[0003] One problem associated with pure copper interconnects concernsabnormal grain growth or thermal stability in the deposited film.Further, such abnormal and undesired grain growth can reduce the film'selectromigration resistance. Low thermal stability is defined as, andabnormal grain growth is characterized by, a tendency of the individualcrystal grains within copper to grow when exposed to a certaintemperature. The higher the temperature at which a materialrecrystallizes or starts to grow larger grains, the higher the thermalstability of the material.

[0004] Elemental copper and its alloys can be deposited in integratedcircuitry fabrication using a number of techniques, including chemicalvapor deposition, physical vapor deposition and electrochemicaldeposition, such as electroplating. Ideally when deposited, the coppercomprising sputtering target will have substantially uniformmicrostructure, a fine grain size, and preferred crystal orientation inorder to achieve desired sputtering performance and resultant thin filmformation and properties.

SUMMARY

[0005] The invention includes conductive integrated circuit metal alloyinterconnections, physical vapor deposition targets and electroplatinganodes. In one implementation, a physical vapor deposition targetincludes an alloy of copper and silver, with the silver being present inthe alloy at from less than 1.0 at % to 0.001 at %. In oneimplementation, a physical vapor deposition target includes an alloy ofcopper and silver, with the silver being present in the alloy at from 50at % to 70 at %. In one implementation, a physical vapor depositiontarget includes an alloy of copper and tin, with tin being present inthe alloy at from less than 1.0 at % to 0.001 at %.

[0006] In one implementation, a conductive integrated circuit metalalloy interconnection includes an alloy of copper and silver, with thesilver being present in the alloy at from less than 1.0 at % to 0.001 at%. In one implementation, a conductive integrated circuit metal alloyinterconnection includes an alloy of copper and silver, with the silverbeing present in the alloy at from 50 at % to 70 at %. In oneimplementation, a conductive integrated circuit metal alloyinterconnection includes an alloy of copper and tin, with tin beingpresent in the alloy at from less than 1.0 at % to 0.001 at %.

[0007] In one implementation, an electroplating anode includes an alloyof copper and silver, with the silver being present in the alloy at fromless than 1.0 at % to 0.001 at %. In one implementation, anelectroplating anode includes an alloy of copper and silver, with thesilver being present in the alloy at from 50 at % to 70 at %. In oneimplementation, an electroplating anode includes an alloy of copper andtin, with tin being present in the alloy at from less than 1.0 at % to0.001 at %.

[0008] In other implementations, other useable copper alloys in physicalvapor deposition targets, conductive integrated circuit metal alloyinterconnections, and electroplating anodes include an alloy of copperand one or more other elements, the one or more other elements beingpresent in the alloy at a total concentration from less than 1.0 at % to0.001 at % and being selected from the group consisting of Be, Ca, Sr,Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, Te, V, Nb, Ta, Cr, Mo, W, Mn, Tc,Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Au, Ti, and Pb. An electroplatinganode is formed to comprise one or more of the above alloys.

[0009] In other implementations, the invention contemplates metal alloysfor use as a conductive interconnection in an integrated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

[0011]FIG. 1 is a diagrammatic sectional view of a physical vapordeposition target system in accordance with an aspect of the invention.

[0012]FIG. 2 is a diagrammatic sectional view of an electroplatingsystem incorporating an electroplating anode in accordance with anaspect of the invention.

[0013]FIG. 3 is a cross-sectional view of a semiconductor wafer fragmentcomprising integrated circuitry including a conductive metal alloyinterconnection in accordance with an aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] This disclosure of the invention is submitted in furtherance ofthe constitutional purposes of the U.S. Patent Laws “to promote theprogress of science and useful arts” (Article 1, Section 8).

[0015] The present invention includes novel physical vapor depositiontargets comprising alloys of copper and silver, and comprising alloys ofcopper and tin. The invention also contemplates conductive integratedcircuit interconnections comprised of such metal alloys, and whetherdeposited utilizing the inventive physical vapor deposition targets, bychemical vapor deposition or by other methods. The invention includeselectroplating anodes comprising alloys of copper and silver, andcomprising alloys of copper and tin. The invention also includesphysical vapor deposition targets, conductive integrated circuitinterconnections, and electroplating anodes comprising other copperalloys. The invention also contemplates metal alloys for use as aconductive interconnection in an integrated circuit, by way of exampleonly as might be used as raw material for producing physical vapordeposition targets or electroplating anodes.

[0016] In one implementation, a physical vapor deposition targetcomprises an alloy of copper and silver, with the silver being presentin the alloy at from less than 1.0 at % to 0.001 at %, and morepreferably at from 0.005 at % to 0.1 at %. An aspect of the inventionalso includes a conductive integrated circuit metal alloyinterconnection comprising this alloy of copper and silver. Preferably,such interconnection will have higher electromigration resistance thancopper of a purity greater than 99.999% of the same grain size. Furtherpreferably, the alloy will have greater thermal stability to grain sizeretention and crystal orientation retention than copper of a purity ofgreater than 99.999% of the same grain size. Further preferably, verynear the pure copper electrical conductivity is ideally achieved.Preferably when the interconnection is deposited from a sputteringtarget, the alloy offers very stable sputtering target microstructureand texture. A thermally stabilized target of this alloy can offerimproved sputtering performance and resultant thin film propertieswithin the circuitry. Regardless and when deposited from chemical vapordeposition or other methods, the alloy offers higher electromigrationresistance while maintaining very near the pure copper electricalconductivity. Silver can form uniformly fine precipitates in themicrostructure in the form of elemental precipitates.

[0017] In another aspect of the invention, the physical vapor depositiontarget comprises an alloy of copper and silver, with silver beingpresent in the alloy at from 50 at % to 70 at %, more preferably atbetween 55 at % and 65 at %, and most preferably at about 60 at %. Theinvention also contemplates a conductive integrated circuit metal alloyinterconnection comprising this alloy of copper and silver, whetherdeposited by physical vapor deposition, chemical vapor deposition orother methods. Most preferably, the resultant alloy as formed in thecircuit has higher electromigration resistance than copper of a purityof greater than 99.999% of the same grain size. Further preferably, thealloy interconnection preferably has greater thermal stability to grainsize retention and crystal orientation retention than copper of a purityof greater than 99.999% of the same grain size.

[0018] Silver is a very desirable doping element in copper for physicalvapor deposition targets and conductive integrated circuity metal alloyinterconnections, as it has a similar electrical resistivity with copperand forms essentially no solid solution with copper. Accordingly, acopper-silver alloy can be largely represented as a mechanical mixtureof silver grains and copper grains. Due to this structure and mixture, acopper-silver alloy has minimum electrical resistivity increase overthat of pure copper even at high-level silver concentrations. Further,it is reported that the lowest electrical resistivity of copper-silveralloys is close to the eutectic composition, which is at about copper at40 at %, silver at 60 at %, and is only about 10% above the resistivityof pure copper. Accordingly, a considerably reduced or lower reflowtemperature can be achieved using a copper alloy at or about the 60 at %silver eutectic point for the alloy. This will result in a melttemperature of about 780° C., which is considerably lower than a purecopper melt temperature of about 1085° C., and is only about 120° C.above the melt temperature for aluminum and alloys thereof commonlypresently used in conductive integrated circuit interconnections.Accordingly, the low-melt temperature of the eutectic alloy presents anopportunity for low. temperature reflow after thin film deposition forsmall via and deep trench-fill applications.

[0019] This particular application could have a profound impact on thinfilm deposition. With the ever shrinking device feature size andintegrated circuitry design rules, one of the bottlenecks for thin filmdeposition is the complete filling of small via and trenches. Pressureor temperature-assisted film deposition has been adopted to leverage thedifficulty of small via and trench-fill in aluminum metallization.However, high pressure is not well-compatible with conventionalintegrated circuitry processes, and therefore has not been very wellaccepted by the industry. Accordingly, predominantly high temperatureprocessing has been used in most applications. Yet for coppermetallization, the temperature-assisted deposition is not expected to bepractical due to its high melt temperature. Yet, copper-silver alloys atthe preferred composition range between 50 at % and 70 at % silver, andeven more preferably at around the eutectic point of 60 at % silver, mayprovide significant processing advantages in using copper alloys.

[0020] In another aspect of the invention, a physical vapor depositiontarget comprises an alloy of copper and tin, with tin being present inthe alloy at from less than 1.0 at % to 0.001 at %, and more preferablyat from 0.01 at % to 0.1 at %. An aspect of the invention alsocontemplates conductive integrated circuitry metal alloyinterconnections comprising this alloy. Preferably, suchinterconnections will have higher electromigration resistance thancopper of a purity of greater than 99.999% of the same grain size.Further preferably, such interconnections will have greater thermalstability to grain size retention and crystal orientation retention thancopper of a purity of greater than 99.999% of the same grain size.Further preferably, the interconnections will have an electricalresistivity of less than 1.8 microohms.cm. Tin can form uniformly fineprecipitates in the microstructure in the form of intermetallic compoundprecipitates.

[0021] A series of copper alloys were prepared using conventional vacuuminduction melt and air melt methods. A high purity copper (purity of99.9998% (5N8)) was used as a reference, as well as the startingmaterial for the copper alloys described above. Different levels ofsilver and tin were doped into the reference copper to obtain the copperalloys. Chemical analysis was taken from the as-cast samples using glowdischarge mass spectroscopy (GDMS). Thermal stability was evaluatedusing hardness, grain size, and texture (grain orientation) analysis atdifferent temperatures. Electrical resistivity was measured using bulksamples at room temperature.

[0022] The detailed results are shown in the tables below, with all ppmvalues being in weight percent. Electrical Resistivity Material (μΩ.cm)Pure Cu (5N8) 1.70 Cu w/16 ppm Sn 1.71 Cu w/530 ppm Sn 1.69 Cu w/135 ppmAg 1.82 Cu w/145 ppm Ag 1.75 Cu w/385 ppm Ag 1.75

[0023] Recrystallization Material Temperature (° C.) Pure Cu (5N8) 150Cu w/350 ppm Sn 250 Cu w/530 ppm Sn 300 Cu w/145 ppm Ag 350 Cu w/385 ppmAg 400

[0024] Grain Size Retention Texture Retention Material Temperature (°C.) Temperature (° C.) Pure Cu (5n8)   350 (grain size 30 μm) 150 Cuw/530 ppm Sn >400 (grain size 20 μm) 300 Cu w/385 ppm Ag >400 (grainsize 20 μm) 400

[0025] The above reduction-to-practice examples show tin andsilver-copper alloys having approximately the same electricalresistivity as pure copper. Further, such copper alloys demonstrateimproved thermal stability and refined grain structure.

[0026] Both silver and tin have negligible solid solubility in copper atroom temperature. Accordingly, almost all of the doped silver and tinpreferably precipitates out of the copper matrix once the alloy issolidified. A preferred result is a virtually clean copper matrix with asmall amount of silver or CuSn₃ intermetallic compounds. Preferably,there is little copper lattice distortion in very small amount ofprecipitates, leaving the electrical resistivity very close to purecopper. This trend should result where the doping element does not formsolid solution with copper, and its amount is less than 1 at % silver ortin.

[0027] The invention also contemplates use of other copper alloys inphysical vapor deposition targets, conductive integrated circuitinterconnections, and electroplating anodes. These materials includeelements which have low room temperature solid solubility and uniformlydistributed fine precipitates in the microstructure, much like silverand tin. One class of elements forms intermetallic compound precipitatesin the microstructure. These include Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr,Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B,Ga, In, C, Se, and Te. In accordance with an aspect of the invention,physical vapor deposition targets, conductive integrated circuitinterconnections, and electroplating anodes are comprised of an alloy ofcopper and one or more other elements, with the one or more otherelements being present in the alloy at a total concentration from lessthan 1.0 at % to 0.001 at % and being selected from the group consistingof Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho,Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, and Te. Suchcopper alloys are expected to have higher electromigration resistancethan copper of a purity of greater than 99.999% of the same grain size.Further, such copper alloys are expected to have greater thermalstability to grain size retention and crystal orientation retention thancopper of a purity of greater than 99.999% of the same grain size.

[0028] Another class of elements forms element precipitates in themicrostructure. These include V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru,Os, Co, Rh, Ni, Pd, Pt, Au, Tl, and Pb. In accordance with an aspect ofthe invention, physical vapor deposition targets, conductive integratedcircuit interconnections, and electroplating anodes are comprised of analloy of copper and one or more other elements, with the one or moreother elements being present in the alloy at a total concentration fromless than 1.0 at % to 0.001 at % and being selected from the groupconsisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ni,Pd, Pt, Au, Tl, and Pb. Such copper alloys are expected to have higherelectromigration resistance than copper of a purity of greater than99.999% of the same grain size. Further, such copper alloys are expectedto have greater thermal stability to grain size retention and crystalorientation retention than copper of a purity of greater than 99.999% ofthe same grain size.

[0029]FIG. 1 diagrammatically depicts a sputtering system comprising asputtering assembly 20 and a wafer 22 to be sputter deposited upon.Sputtering assembly 20 comprises a main sputtering target 24 adhered toa backing plate 26 by conventional or yet-to-be developed methods.Sputtering assembly 20 also includes an RF sputtering coil 28 receivedintermediate main target 24 and substrate 22. One or both of main target24 and RF sputtering coil 28 is fabricated to comprise one or more ofthe above alloys.,

[0030] In one aspect, the invention also contemplates use of one or moreof the above alloys as an electroplating anode. FIG. 2 diagrammaticallydepicts but an exemplary electroplating system 30 comprising a liquidreservoir 31. A substrate 32 to be deposited upon and an electroplatinganode 34 are received within a suitable plating solution withinreservoir 31 opposite one another. Substrate 32 and anode 34 areelectrically interconnected with one another through a suitable powersource 36 configured to enable substrate 32 to function as a cathode,and thereby deposit material from electroplating anode 34 onto substrate32.

[0031]FIG. 3 illustrates but an exemplary semiconductor wafer fragmentindicated generally with reference numeral 10. Such comprises a bulksemiconductive substrate 12 having an electrically conductive diffusionregion 14 formed therein. An electrically insulating layer 16 is formedover substrate 12 and a contact opening 18 has been formed therethroughover diffusion region 14. Such has been plugged with an electricallyconductive plugging material 25, which preferably comprises one or moreof the alloys as described above. Diffusion barrier or adhesion layers(not shown) might also, of course, be utilized relative to contactopening 18. An electrically conductive line 26 has been deposited andpatterned over and in electrical connection with conductive pluggingmaterial 25. Interconnect line 26 also preferably comprises one or moreof the above-described alloys. Components 26 and 25 constitute exemplaryconductive integrated circuit metal alloy interconnections preferablycomprising one or more of the alloys described herein. Such mightcomprise different materials as depicted by the different section lines,or constitute the same material throughout. Other constructions are ofcourse contemplated.

[0032] In compliance with the statute, the invention has been describedin language more or less specific as to structural and methodicalfeatures. It is to be understood, however, that the invention is notlimited to the specific features shown and described, since the meansherein disclosed comprise preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A conductive integrated circuit metal alloy interconnection comprising an alloy of copper and silver, with silver being present in the alloy at from less than 1.0 at % to 0.001 at %.
 2. The interconnection of claim 1 wherein silver is present in the alloy at from 0.005 at % to 0.1 at %.
 3. The interconnection of claim 1 having higher electromigration resistance than copper of a purity of greater than 99.999% of the same grain size.
 4. The interconnection of claim 1 having greater thermal stability to grain size retention and crystal orientation retention than copper of a purity of greater than 99.999% of the same grain size.
 5. A physical vapor deposition target comprising an alloy of copper and silver, with silver being present in the alloy at from less than 1.0 at % to 0.001 at %.
 6. The physical vapor deposition target of claim 5 wherein silver is present in the alloy at from 0.005 at % to 0.1 at %.
 7. The physical vapor deposition target of claim 5 comprising an RF sputtering coil.
 8. An electroplating anode comprising an alloy of copper and silver, with silver being present in the alloy at from less than 1.0 at % to 0.001 at %.
 9. The electroplating anode of claim 8 wherein silver is present in the alloy at from 0.005 at % to 0.1 at %.
 10. A metal alloy for use as a conductive interconnection in an integrated circuit comprising copper and silver, with silver being present in the alloy at from less than 1.0 at % to 0.001 at %.
 11. The metal alloy of claim 10 wherein silver is present in the alloy at from 0.005 at % to 0.1 at %.
 12. A conductive integrated circuit metal alloy interconnection comprising an alloy of copper and silver, with silver being present in the alloy at from 50 at % to 70 at %.
 13. The interconnection of claim 12 wherein silver is present in the alloy at from 55 at % to 65 at %.
 14. The interconnection of claim 12 wherein silver is present in the alloy at about 60 at %.
 15. The interconnection of claim 12 having higher electromigration resistance than copper of a purity of greater than 99.999% of the same grain size.
 16. The interconnection of claim 12 having greater thermal stability to grain size retention and crystal orientation retention than copper of a purity of greater than 99.999% of the same grain size.
 17. A physical vapor deposition target comprising an alloy of copper and silver, with silver being present in the alloy at from 50 at % to 70 at %.
 18. The physical vapor deposition target of claim 17 wherein silver is present in the alloy at from 55 at % to 65 at %.
 19. The physical vapor deposition target of claim 17 wherein silver is present in the alloy at about 60 at %.
 20. The physical vapor deposition target of claim 17 comprising an RF sputtering coil.
 21. An electroplating anode comprising an alloy of copper and silver, with silver being present in the alloy at from 50 at % to 70 at %.
 22. The electroplating anode of claim 21 wherein silver is present in the alloy at from 55 at % to 65 at %.
 23. The electroplating anode of claim 21 wherein silver is present in the alloy at about 60 at %.
 24. A metal alloy for use as a conductive interconnection in an integrated circuit comprising copper and silver, with silver being present in the alloy at from 50 at % to 70 at %.
 25. The metal alloy of claim 24 wherein silver is present in the alloy at from 55 at % to 65 at %.
 26. A conductive integrated circuit metal alloy interconnection comprising an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %.
 27. The interconnection of claim 26 wherein tin is present in the alloy at from 0.01 at % to 0.1 at %.
 28. The interconnection of claim 26 having higher electromigration resistance than copper of a purity of greater than 99.999% of the same grain size.
 29. The interconnection of claim 26 having greater thermal stability to grain size retention and crystal orientation retention than copper of a purity of greater than 99.999% of the same grain size.
 30. The interconnection of claim 26 having an electrical resistivity of less than 1.8 microohms.cm.
 31. A physical vapor deposition target comprising an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %.
 32. The physical vapor deposition target of claim 31 wherein tin is present in the alloy at from 0.01 at % to 0.1 at %.
 33. The physical vapor deposition target of claim 31 comprising an RF sputtering coil.
 34. An electroplating anode comprising an alloy of copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %.
 35. The electroplating anode of claim 34 wherein tin is present in the alloy at from 0.01 at % to 0.1 at %.
 36. A metal alloy for use as a conductive interconnection in an integrated circuit comprising copper and tin, with tin being present in the alloy at from less than 1.0 at % to 0.001 at %.
 37. The metal alloy of claim 36 wherein tin is present in the alloy at from 0.01 at % to 0.1 at %.
 38. A conductive integrated circuit metal alloy interconnection comprising an alloy of copper-and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, and Te.
 39. The interconnection of claim 38 wherein the one or more other elements are present in the alloy at a total concentration from 0.005 at % to 0.1 at %.
 40. The interconnection of claim 38 having higher electromigration resistance than copper of a purity of greater than 99.999% of the same grain size.
 41. The interconnection of claim 38 having greater thermal stability to grain size retention and crystal orientation retention than copper of a purity of greater than 99.999% of the same grain size.
 42. A physical vapor deposition target comprising an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, and Te.
 43. The physical vapor deposition target of claim 42 wherein the one or more other elements are present in the alloy at a total concentration at from 0.005 at % to 0.1 at %.
 44. The physical vapor deposition target of claim 42 comprising an RF sputtering coil.
 45. An electroplating anode comprising an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, and Te.
 46. The electroplating anode of claim 45 wherein the one or more other elements are present in the alloy at a total concentration at from 0.005 at % to 0.1 at %.
 47. A metal alloy for use as a conductive interconnection in an integrated circuit comprising copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of Be, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ti, Zr, Hf, Zn, Cd, B, Ga, In, C, Se, and Te.
 48. The metal alloy of claim 47 wherein the one or more other elements are present in the alloy at a total concentration from 0.005 at % to 0.1 at %.
 49. A conductive integrated circuit metal alloy interconnection comprising an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Au, Tl, and Pb.
 50. The interconnection of claim 49 wherein the one or more other elements are present in the alloy at a total concentration from 0.005 at % to 0.1 at %.
 51. The interconnection of claim 49 having higher electromigration resistance than copper of a purity of greater than 99.999% of the same grain size.
 52. The interconnection of claim 49 having greater thermal stability to grain size retention and crystal orientation retention than copper of a purity of greater than 99.999% of the same grain size.
 53. A physical vapor deposition target comprising an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Au, Tl, and Pb.
 54. The physical vapor deposition target of claim 53 wherein the one or more other elements are present in the alloy at a total concentration at from 0.005 at % to 0.1 at %.
 55. The physical vapor deposition target of claim 53 comprising an RF sputtering coil.
 56. An electroplating anode comprising an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Au, Tl, and Pb.
 57. The electroplating anode of claim 56 wherein the one or more other elements are present in the alloy at a total concentration at from 0.005 at % to 0.1 at %.
 58. A conductive integrated circuit metal alloy interconnection comprising an alloy of copper and one or more other elements, the one or more other elements being present in the alloy at a total concentration from less than 1.0 at % to 0.001 at % and being selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Au, Tl, and Pb.
 59. The interconnection of claim 58 wherein the one or more other elements are present in the alloy at a total concentration from 0.005 at % to 0.1 at %. 